/*
 *  Copyright (c) 2004, The Joust Project
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions 
 *  are met:
 *
 *  - Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *  - Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in 
 *    the documentation and/or other materials provided with the 
 *    distribution. 
 *  - Neither the name of the Joust Project nor the names of its 
 *    contributors may be used to endorse or promote products derived 
 *    from this software without specific prior written permission. 
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
 *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 *  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
 *  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 *  POSSIBILITY OF SUCH DAMAGE.
 *
 *  File created by keith @ Feb 25, 2004
 *
 */

package net.kano.joustsim.text.convbox;

import javax.swing.JViewport;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Point;

public class BottomScrollingViewport extends JViewport {
    private int distFromBottom = 0;
    private boolean ignore = false;

    public void doLayout() {
        ignore = true;
        super.doLayout();
        ignore = false;
    }

    public void reshape(int x, int y, int w, int h) {
        updateViewPosition(h);
        ignore = true;
        super.reshape(x, y, w, h);
        ignore = false;
    }

    public void setViewPosition(Point p) {
        ignore = true;
        super.setViewPosition(p);
        ignore = false;
        updateDistFromBottom();
    }

    public void setViewSize(Dimension newSize) {
        updateViewPosition(getHeight());
        ignore = true;
        super.setViewSize(newSize);
        ignore = false;
    }

    private void updateViewPosition(int h) {
        Point vp = getViewPosition();
        int viewHeight = getView().getHeight();
        vp.y = Math.max(0, viewHeight - h - distFromBottom);

        setViewPosition(vp);
    }

    private void updateDistFromBottom() {
        if (ignore) return;
        Component view = getView();
        Point viewPosition = getViewPosition();
        if (view == null || viewPosition == null) return;
        distFromBottom = view.getHeight()
                - (viewPosition.y + getHeight());
    }
}
